Trains run all hours of the day -- though far less frequently during the wee hours of the morning. See the MTA Web site for Port Washington Line schedules.
A station house provides a space for commuters and sojourners to wait on weekdays from 6 a.m. to 1:45 p.m., and Saturdays from 6:25 a.m. to 2 p.m. Tickets can be purchases in machines outside -- and should be purchased before boarding to avoid an extra fee for buying aboard the train.